Modified thermoplastic phenolic resin adhesive used in automobile brake pad and preparation method thereof

Abstract

The invention provides a modified thermoplastic phenolic resin adhesive used in automobile brake pads and a preparation method thereof. The adhesive is prepared from following components, by weight: 100 parts of phenols, 73-80 parts of aldehydes, 0.05-0.08 parts of acids, 1-7 parts of nano organic modified montmorillonite, 2-4 parts of D-glucose and 1-7 parts of dialdehydes. The preparation method comprises following steps: (A) adding the nano organic modified montmorillonite and the acid into a reaction container according to ratio and stirring the mixture for 30 min at 50-60 DEG C; (B) increasing the temperature to 90-100 DEG C, adding 73-80 parts of aldehydes to the reaction liquid within 60-90 min, and continuously performing the reaction with temperature maintained for 30-60 min; (C) adding 2-4 parts of D-glucose to the reaction liquid, and performing a reaction for 10-20 min at 90-100 DEG C; (D) adding 1-7 parts of dialdehydes to the reaction liquid,, and performing a reaction at 90-100 DEG C for 25-40 min; and (E) starting a vacuum pump to control the pressure in the reaction container to be -0.08 MPa, and performing dehydration for 5 h to prepare the modified thermoplastic phenolic resin adhesive. The method increases the heat resistance and toughness of phenolic resin and reduces the contents of free phenols and volatiles in the resin.

Description

technical field [0001] The invention belongs to the technical field of polymer materials, and in particular relates to a modified thermoplastic phenolic resin for automobile brake pads and a preparation method thereof. Background technique [0002] The braking system is the most important safety system of the automobile, and the automobile brake pad is an important part of the entire braking system. Its performance directly affects the reliability of the braking system and the life safety of the operator. When the car is braking, the temperature of the brake pads will rise to 400°C or higher. Therefore, there are higher requirements for the high-temperature performance of the brake pads. Automobile brake pads are mainly composed of adhesives, fiber reinforced materials, friction modifiers and fillers, which are mixed with four major components and then hot-pressed. Among them, the binder is one of the most important components in the brake pads. It directly affects the ther...

AI Technical Summary

Problems solved by technology

[0003] Phenolic resin is a common adhesive for automobile brake pads. It has good compressive strength, water resistance, acid resistance and other properties, but it also has disadvantages, such as high brittleness, poor heat resistance under high temperature and variable temperature conditions. Poor material adhesion, etc., make the friction material based on phenolic resin too high in hardness (HB>50), lower in impact strength, severe thermal recession, unstable friction and wear properties, and prone to interface cracks

The main reasons for the unstable performance of the resin are: ①The aromatic rings in the resin structure are mainly connected by methine groups, which are rigid structures, which easily lead to low toughness of the resin

②The molecular structure of phenolic formaldehyde lacks groups with strong cohesive force, which makes the cohesiveness of the resin poor

③The free phenol in the resin can easily generate quinone or other structures when heated or under the action of ultraviolet light, which greatly reduces the heat resistance and other properties of the resin

[0004] Chinese patent ZL201210521313.2 uses polyvinyl alcohol, nano-scale attapulgite and micron-scale copper powder to modify water-soluble phenolic resin, which improves the heat resistance, wear resistance and toughness of the resin, but does not reduce the free phenol in the resin content, while the addition of attapulgite will reduce the fluidity of the resin

[0005] Chinese patent ZL201210129746.3 uses 1 part of phenol, 0.7-0.8 part of aldehyde, 0.0008 part of acid and 0.02-0.04 part of methyl glucoside as raw materials to prepare modified thermoplastic phenolic resin, which improves the heat resistance of the resin to a certain extent. The free phenol content has been reduced, but it still cannot meet the needs. At the same time, the volatile matter content in the modified phenolic resin obtained is relatively high, and the toughness is low